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**[4910 -**  **13 -**  **P] DEPARTMENT OF TRANSPORTATION**  **Federal Aviation Administration 14 CFR Part 39**  **[Docket No. FAA -**  **20 08**  **- 0442**  **; Directorate Identifier 2007**  **- SW**  **- 24**  **- AD]**  **RIN 2120 -**  **AA64 Airworthiness**  **Directives** ; **Various Sikorsky -**  **Manufactured Transport and Restricted Category Helicopters**  **AGENCY:** Federal Aviation Administration (FAA), DOT. **ACTION:** Supplemental notice of proposed rulemaking ( S NPRM); reopening of comment period. **SUMMARY:** We are revising th e propos als in an earlier notice of proposed rulemaking (NPRM) for certain Sikorsky Aircraft Corporation (Sikorsky) Model S - 61A, D, E, L , N, NM (serial number 61454), R, and V; Croman Corporation Model SH - 3H, Carson Helicopters, Inc., Model S - 61L ; Glacier Helicopters, Inc. Model CH - 3E; Robinson Air Crane, Inc. Model CH - 3E, CH - 3C, HH - 3C, and HH - 3E; and Siller Helicopters Model CH - 3E and SH - 3A h elicopters . The NPRM proposed superseding an existing AD but retaining some requirements of that AD, removing certai n dowel pin bores, expanding the applicability

to include additional helicopters, and implementing a new retirement life for each main rotor shaft (MRS) based on a reevaluation of the MRS service life. This SNPRM is prompted by

the comments received in res ponse to the NPRM and a reevaluation of the relevant data. The proposed actions are intended to prevent MRS2

structural failure, loss of power to the main rotor, and subsequent loss of control of the helicopter. **DATES:** We must receive comments on this SNPRM by [I NSERT DATE 60 DAYS AFTER DATE OF PUBLICATION IN THE FEDERALREGI STER]. **ADDRESSES:** You may send comments by any of the following methods: • Federal eRulemaking Docket : Go to http://www.regulations.gov . Follow the instructions for s ending your comments electronically . • Fax : 202 - 493 - 2251. • Mail : Send comments to the U.S. Department of Transportation, Docket Operations, M - 30, West Building Ground Floor, Room W12 - 140, 1200 New Jersey Avenue SE., Washington , DC 20590 - 0001 . • Hand Delivery : Deliver to the “Mail” address between 9 a.m. and 5 p.m., Monday through Friday , except Federal holiday s. **Examining the AD Docket** You may examine the AD docket on the Internet at http://www.regulations.gov or in person at the Docket Management Facilit y between 9 a.m. and 5 p.m., Monday through Friday , except Federal holiday s. The AD docket contains this proposed AD, the regulatory

evaluation, any

comments received, and other inform ation. The street address for the Docket Office (phone: 800 - 647 - 5527) is in the ADDRESSES section. C omments will be available in the AD docket shortl y after receipt. For service information identified in this AD, contact Sikorsky Aircraft Corporation, Attn: Manager, Commercial Technical Support, mailstop s581a, 6900 Main Street, Stratford, C T , telephone (203) 383 - 4866, e - mail address tsslibrary @sikorsky .com ,3

or at http: //www.sikorsky.com . You may review a cop y of the referenced service information at the FAA, Office of the Regional Counsel , 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. **FOR FURTHER INFORMATION CONTACT** : Jeffrey L ee, Aviation Safet y Engineer, Bost on Aircraft Certification Office, 12 New England Executive Park, Burlington, MA 01803, telephone (781) 238 - 7161, fax (781) 238 - 7170 , email jeffrey .lee@faa.gov . **SUPPLEMENTARY INFORMATION: Comments Invited**  We invite you to participate in this rulemaking b y submitting written comments, data, or views. We also invite comments relating to the economic, environmental, energy , or federalism impacts that might result from adopting the proposals in this document. The most helpful comments reference a specific porti on of the proposal, explain the reason for any recommended change, and include supporting data. To ensure the docket does not contain duplicate comments, commenters should send only one copy of written comments, or if comments are filed electronically , commenters should submit only one time. We will file in the docket all comments that we receive, as well as a report summarizing each substantive public contact with FAA personnel concerning this proposed rulemaking. Before acting on this proposal, we will c onsider all comments we receive on or before the closing date for comments. We will consider comments filed after the comment period has closed if it is possible to do so without incurring expense or delay . We may

change this proposal in light of the comme nts we receive.4

**Discussion** On April 10, 2008, w e issued an NPRM (73 FR 21556, April 22, 2008) proposing to amend 14 CFR part 39 to include an AD for Sikorsky Aircraft Corporation Model S - 61A, D, E, L, N, NM, R, and V; Croman Corporation Model SH - 3H, Carson Helicopters, Inc. Model S - 61L ; Glacier Helicopters, Inc. Model CH - 3E; Robinson Air Crane, Inc. Model CH - 3E, CH - 3C, HH - 3C and HH - 3E; and Siller Helicopters Model CH - 3E and SH - 3A h elicopters. That NPRM proposed superseding AD 98 - 26 - 02, published in the Fede ral Register on December 16, 1998 (63 FR 69177), that only applied to the affected Sikorsky model helicopters. That NPRM proposed retaining some of the requirements of the existing AD but also proposed determining a new retirement life for each MRS , removi ng from service an y MRS with oversized dowel pin bores , and expanding the applicability to include certain restricted category models that were inadvertentl y omitted in the current A D. That NPRM was prompted by the manufacturer’s reevaluation of the retire ment life for the MRS based on torque, ground air - ground (GAG) cycle, and fatigue testing. Those proposals were intended to prevent MRS structural failure, loss of power to the main rotor, and subsequent loss of control of the helicopter. **Actions Since Pre vious NPRM was Issued**  Since we issued the NPRM (73 FR 21556, April 22, 2008) , we have d etermined a need to revise the proposed r equirements , based on our review of the data and the comments received. Th ese supplemental proposals are intended to extend the hours time - in - service ( TI S ) required for identifying the MRS as a repetitive external lift ( REL ) MRS to coincide with the nondestructive inspection (NDI) so that onl y one disassembly5

of the shaft is required, which would reduce the down time re quired to disassemble the shaft. Also, this action proposes to extend the time required to replace the MRS. This action also proposes to modify a paragraph in the AD that imposes a factor of 30 for unknown flight time . This has been changed to a factor of 13.6 . This action proposes to add the determination of the shaft cy cle count for the purpose of establishing the life limit. Also, this action proposes to a llow additional Revision A service information that can be used to modify an REL MRS for its life l imit determination. We are reopening the comment period to allow the public to comment on these proposed changes. **Comments** We gave the public the opportunity to comment on the previous NPRM (73 FR 21556, April 22, 2008) . The following presents the comments received on the NPRM, and the FAA’s response to those comment s . **Request** One commenter stated there was a difference between AD 98 - 26 - 02 and the NPRM in how many

lifts constitute the shaft being REL. The commenter stat ed that a shaft that had 6 lifts per hour is RELunder AD 98 - 26 - 02 but would not be considered REL (more than 6 lift cycles per hour) under the NPRM. We agree . The proposed AD is changed to match AD 98 - 26 - 02. Those shafts that have 6 or more lifts per hour are REL shafts . Two commenters commented on the requirement to identify the REL MRS . One commenter stated that the compliance time to identify the REL MRS should be extended from 5 hours to 10 hours. Another commenter asked if the i dentification of REL MRS on6

the component history

card w ould be sufficient and stated that the marking requirement of the RELMRS would require an extended down time and lost revenue . We partially

agree. We still believe the phy sical RELMRS should be identified and marking the component history card alone is insufficient . However, to avoid unnecessary

down time, we are proposing to mark the MRS to coincide with the NDI at 1,100 hours TI S, at which time , the shaft would be disassembled an yw ay thus avoiding unnecessarily

disass embling the MRS just to mark it . One commenter stated that mentioning the identification of the TS - 281 marking in the proposed “Note 2” could result in a serviceable MRS being rejected. The commenter further states that an MRS can have the TS - 281 marking but not have oversized dowel pin holes. We disagree. The proposed AD would not require all shafts marked with the TS - 281 marking to be removed from service. Only those shafts that have oversized dowel pin bores would be required to be removed from service . A commenter stated that compliance time (grace period) should be extended for the MRS over life limit because the steel plates referenced in the service information may not be available. Another commenter , the manufacturer, further stated that cycle lim its should be added to the grace period. We dis agree. Providing a grace period within which to comply with a retirement life essentially

extends the retirement life and would not be appropriate . Also, this AD does not mandate modifying the configuration u sing the steel plates in SB 61B35 - 53A, and therefore the availability of that part does not factor into the compliance times identified.7 Another commenter stated that the lack of documented failures supports keeping the existing life limits in place and d oes not support the additional cycle limits to the MRS due to flawed testing. The commenter further stated that there have been no reported cracks in the MRS in the 9+ y ears since issuing AD 98 - 26 - 02. The commenter also stated that the life limits were ge nerated using a flawed test program. Based on an approved Rotorcraft Flight Manual, the chart shows that at above 20 degrees Celsius and 1000 - foot pressure altitude, the helicopter cannot produce 103 per cent torque. The capability of the helicopter reachi ng 103 percent torque was one of the reasons the commenter gave that the testing was flawed. Due to that capability , the testing at the 96 percent torque value was indicated to be more realistic (the test specimen lasted for longer than 1.4 million cycles) . The second example of flawed testing given by the commenter was that using the 200,000 cycle in the presentation and without using the mean or working curve, the factor of 30 gives an equivalent time of over 6,660 flight hours. This would allow several 1 000 - hour inspections based on the overhaul manual to remove an y of the fretting damage. Therefore, the fretting damage would have been repaired, resulting in a significant increase in cycles to failure. We partially agree. During certain operations, the h elicopter can reach 103 percent torque depending on the temperature and altitude adjustments. The ability of the helicopter to reach 103 percent torque was one of the reasons given for flawed testing. Based on logging surveys conducted b y Sikorsky, the cur rent usage spectrum of some operators exceeds those that generated the MRS life limits. However, there have been no new reported cracks. During the time histories of engine torque available during an operator logging survey , the 103 per cent engine torque was seen during those operations.8

Because the torque value can be reached during logging operations , it is a realistic torque value for determining the new life limit. The second example provided of flawed testing is based on inspecting the specimen b y fo llowing the overhaul manual and repairing any damage. However, when performing fatigue tests for life limit certification of the helicopter, these tests are carried out for the life of the part without any stoppage for inspections or repairs. The allowable cycles are further reduced due to the limited number of test specimens to represent the manufacturing variability and other unknown factors. Therefore, those cy cles are modified using a reduction factor to determine a life limit. Since the testing to dete rmine life limits does not consider repairs, the testing performed was not flawed. Therefore, w e are proposing to retain the new life limits. The same commenter stated that the lack of documented failures supports keeping the existing life limits in place and does not support the additional cycle limits to the MRS because the 30,000 cy cle limit would reduce the actual flight hour time to as low as 1,000 hours (using imposed 30 cy cles per flight hour factor). The commenter further stated that the significant decrease in life limit from 2,200 hours to 1,000 hours is not justified. W e partially

agree. Providing the factor of 30 to the unknown flight time to determine the component lift cycle count would reduce the existing life limit to below those of AD 98 - 2 6 - 02. Therefore, we are modifying the requirements by imposing a factor of 13.6 for the lift cy cle count to the unknown flight time . The manufacturer stated that we should require incorporating Customer Service Notice ( CSN ) 6135 - 10A and Alert Service Bull etin ( ASB ) 61B35 - 53A for unmodified9

RELMRS and reference these instead of the prior revisions. The commenter further state d that we should require replacing the planetary assembl y and MRS assembly attaching hardware with the high strength steel hardware for unmodified RELMRS because the titanium planetary plates have a history

of crack s in RELoperations. We partially

agree. The titanium plates continue to be airworthy so long as the compliance time s for the unmodified RELMRS times are followed. Becaus e they are still airworth y parts, incorporating CSN 6135 - 10A and ASB 61B35 - 53A, both dated April 29, 2004, will not be required for unmodified REL MRS . Operators continuing to use the unmodified RELMRS will continue to have a lower life limit as identifie d in AD 98 - 26 - 02 for the unmodified RELMRS in comparison to the life of a modified RELMRS . However, the later versions of the CSN and ASB (Revision A) will not be incorporated because that is unnecessary to correct the unsafe condition. The previous vers ions are equivalent to CSN 6135 - 10A and ASB 61B35 - 53A for determin ing a modified REL MRS configuration . Therefore, for modified REL MRS, we propose adding CSN 6135 - 10A and ASB 61B35 - 53A to provide credit for those modified by following the original ASB and CSN or revision A to those documents. The manufacturer also stated that the compliance time (grace period) for the non RELMRS should be reduced to 150 from 1500 hours TI S. We disagree. Sikorsky issued ASB 61B35 - 69, which specified replacing a non RELM RS at the next main gearbox overhaul or within 6 months. However, as these shafts have exceeded the life limit for the part, it should be replaced with an airworth y part. Therefore, we are proposing to remove the grace period10

F **AA’s Determination** We are proposing this SNPRM because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other helicopters of these same ty pe designs. Certain changes described above expand the scope of the original NPRM. As a result, we have determined that it is necessary to reopen the comment period to provide additional opportunity for the public to comment on this SNPRM. **Proposed AD Requirements** This proposed AD would retain some of the requirements from the current AD 98 - 26 - 02 (63 FR 69177, December 16, 1998): Recording the number of external lift cycles, determining whether the shaft is REL or non - REL , marking the REL shafts at the time of the NDI, and conducting an NDI for shafts used in RELope rations and replacing it if a crack is found. The proposed AD would also require calculating a 250 - hour TIS moving average of lift cycles to determine whether the MRS is an RELMRS, determine a new retirement life for each MRS based on hour TI S and lift cycles, remove from service any MRS with oversized dowel pin bores, and expand the applicability to include certain restricted category models that were inadvertentl y omitted in the existing AD . Also, this proposed action would extend the retirement life of modified REL MRS from 2,200 hours TI S to 5,000 hours TI S but also implement lift - cycle retirement lives. Lastly , this action proposes allowing the use of Revision A service information to modify the RELMRS for life limit determination.11

**Costs of Compliance** We estimate that this proposed AD would affect 60 helicopters of U.S. registry . We estimate that operators may incur the following costs in order to comply with this p roposed AD: It would take about 2.2 work hours to NDI an REL MRS at $85 per work hour plus a $50 consumable cost, for a total cost of $237 per helicopter and $14,220 for the U.S. fleet. It would take 2.2 work hours at $85 per work hour to replace an MRS, and parts wo uld cost $44,753, for a total cost of $44,940 per helicopter. **Authority for This Rulemaking** Title 49 of the United States Code specifies the FAA’s authority to issue rules on aviation safet y. Subtitle I, section 106, describes the authority of the FAA Adm inistrator. “Subtitle VII: Aviation Programs,” describes in more detail the scope of the Agency ’s authority . We are issuing this rulemaking under the authority described in “Subtitle VII, Part A, Subpart III, Section 44701: General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safet y in air commerce. This regulation is within the s cope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. **Regulatory Findings** We determined that this proposed AD would not have federalism implications under Execut ive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national Government and the States,12

or on the distribution of power and responsibilities among the various levels of government. For the reasons discussed, Icertify this proposed regulation: 1. I s not a “significant regulatory action” under Executive Order 12866; 2. I s not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 3. Will not affect intrastate aviation in Alaska to the extent that it justifies making a regulatory

distinction; and 4. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulato ry Flexibility

Act. We prepared an economic evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket. **List of Subjects in 14 CFR Part 39** Air transportation, Aircraft, Aviation safet y, In corporation by reference, Safe ty . **The Proposed Amendment** Accordingl y, under the authority delegated to me by

the Administrator, the FAA proposes to amend 14 CFR part 39 as follows: **PART 39 -**  **AIRWORTHINESS DIRECTIVES** 1. The authorit y citation for part 39 continues to read as follows: Authority : 49 U.S.C. 106(g), 40113, 44701. **§ 39.13 [Amended]** 2. The FAA amends § 39.13 by removing Amendment 39 - 10943 (63 FR 69177, December 16, 1998), and by adding the following new airworthiness directive ( AD ) :13

**SIKORSKY AIRCRAFT CORPORATION; CROMAN CORP ORATION;**  **CARSON HELICOPTERS, INC.; GLACIER HELICOPTERS, INC.; ROBINSON AIR CRANE, INC.; and SILLER HELICOPTERS**  : Docket No. FAA - 20 08 - 0442 ; Directorate Identifier 2007 - SW - 24 - AD. **(a) Applicability**  **.** This AD applies to Model S - 61A, D, E, L , N, NM (serial number (S/N) 61454), R, V, CH - 3C, CH - 3E, HH - 3C, HH - 3E, SH - 3A, and SH - 3H helicopters with main rotor shaft (MRS), part number (P/N) S6135 - 20640 - 001, S6135 - 20640 - 002, or S6137 - 23040 - 001, installed, certificated in an y cate gory . **(b) Unsafe Condition**  **.** This AD defines the unsafe condition as MRS structural failure, loss of power to the main rotor, and subsequent loss of control of the helicopter . **(c) Affected ADs**  **.** This AD s upersedes AD 98 - 26 - 02 ( 63 FR 69177, December 16, 199 8) , Amendment 39 - 10943, Docket No. 96 - SW - 29 - AD. **(d) Comments Due Date.** We must receive comments by [I NSERT DATE 60 DAYS AFTER DATE OF PUBLICATION IN THE Federal Register]. **( e**  **) Compliance**  **.** You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time. **( f**  **) Required Actions.**  (1) Within 10 hours time - in - service (TIS) :14 (i) C reate a component history card or equivalent record for each MRS. ( ii ) If there is no record of the hours TIS on an individual MRS, substitute the helicopter’s hours TI S. ( iii ) If the record of lift cycles on an individual MRS is incomplete , add the known number of lift cycles to a number calculated by multiplying the number of hours TI S of the individual MRS by the average lift cycles calculated according to the instructions in Section Iof Appendix Iof this AD or by a factor of 13.6, whichever is higher . ( iv ) At the end of each day ’ s operations, record the number of external lift cycles (lift cycles) performed and the hours TI S. An external lift cycle is defined as a flight cycle in which an external load is picked up, the helicopter is repositioned (through flight or hover), and the helicopter hovers and releases the load and departs or lands and departs. (2 ) Within 250 hours TI S, d etermine whether the MRS is a repetitive external lift (REL ) or non - REL MRS. ( i ) C alculate the first moving average of lift cycles by following the instructions in Section Iof Appendix I of this AD. ( A ) If the calculation results in 6 or more lift cycles per hour TI S, the MRS is an REL - MRS. ( B ) If the calculation results in less than 6 lift cycles per hour TI S, the MRS is a Non - RELMRS. ( ii ) If the MRS is a Non - RELMRS based on the calculation perfor med in accordance with paragraph (e)(2)(i) , thereafter at intervals of 50 hour TIS, recalculate the15

average lift cycles per hour TI S by following the instructions in Section II of Appendix 1 of this AD. ( iii ) Once an MRS is determined to be an REL MRS, yo u no longer need to perform the 250 - hour TIS moving average calculation, but you must continue to count and record the lift cycles and number of hours TI S. ( iv ) If an MRS is determined to be an REL MRS, it remains an REL MRS for the rest of its service li fe and is subject to the retirement times for an RELMRS. ( 3 ) W ithin 1,100 hours TIS : (i) C onduct a Non - Destructive Inspection for a crack on each MRS. If there is a crack in an MRS, before further flight, replace it with an airworth y MRS. (ii) If an MR S is determined to be an REL MRS, i dentify it as an RELMRS by etching “REL” on the outside diameter of the MRS near the part S/N by following the Accomplishment Instructions, paragraph 3.C., of Sikorsky Alert Service Bulletin (ASB) 61B35 - 69, dated April 19, 2004. (4) Replace each MRS with an airworth y MRS on or before reaching the revised retirement life as follows: (i) For an REL MRS that is not modified by following Sikorsky Customer Service Notice (CSN) 6135 - 10, dated March 18, 1987, and ASB No. 61B35 - 53, dated December 2, 1981 (unmodified RELMRS), the retirement life is 30,000 lift cy cles or 1,500 hours TI S, whichever occurs first. ( ii ) For an RELMRS that is modified by following Sikorsky CSN 6135 - 10 , dated March 18, 1987 , and Sikorsky ASB No. 61B35 - 53 dated December 2, 1981, or CSN 6135 - 10A , Revision A, and ASB 61B35 - 5 3 A, Revision A, both dated April 19, 200416

(modified RELMRS) , the retirement life is 30,000 lift cycles or 5,000 hours TI S, whichever occurs first. ( iii ) For a non - RELMRS, the retire ment life is 13,000 hours TI S. ( 5 ) E stablish or revise the retirement lives of the MRS as indicated in paragraphs (e) ( 4 )( i ) through (e) ( 4 )( iii ) of this AD by r ecord ing the new or revised retirement life on the MRS component history card or equivalent record. ( 6 ) Within 50 hours TI S, remove from service any MRS with oversized (0.8860” or greater diameter) dowel pin bores. **( g**  **) Alternative Methods of Compliance (AMOCs)**  **.** (1) The Manager, Boston Aircraft Certification Office, FAA, may approve AMOCs for this AD . S end your proposal to Jeffrey L ee, Aviation Safety

Engineer, Boston Aircraft Certification Office, 12 New England Executive Park, Burlington, MA 01803, telephone (781) 238 - 7161, fax (781) 238 - 7170 , email jeffrey .lee@faa.gov . (2) For operations conduct ed under 14 CFR p art 119 oper ating certificate or under 14 CFR part 91, s ubpart K, we suggest that you notify your principal inspector, or lacking a principal inspector, the manager of the local flight standards district office or certificate holding district office before operating an y aircraft complying with this AD through an AMOC. **( h**  **) Additional**  **Information .**  (1) Sikorsky

Aircraft Corporation issued an All Operators Letter (AOL) CCS - 61 - AOL - 04 - 0005, dated May 18, 2004, with an example and additional info rmation about tracking cycles and the moving average procedure. This AOLis not incorporated by reference but contains additional information about the subject of this AD.17 (2) The Overhaul and Repair Instruction (ORI) Number 6135 - 281, Part B, Step 5, and ORI 6137 - 041, Section III, Oversize Dowel Pin Bore Repair and identified on the flange as TS - 281 or TS - 041 - 3 , which is not incorporated b y reference, contains additional information about the subject of this AD. (3) For more information about the AOL or the ORI , contact Sikorsky Aircraft Corporation, Attn: Manager, Commercial Technical Support, mailstop s581a, 6900 Main Street, Stratford, C T , telephone (203) 383 - 4866, e - mail address tsslibrary @sikorsky .com , or at http://www.sikorsky .com . You may review a cop y of the referenced service information at the FAA, Office of the Regional Counsel , 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137.18 APPENDIX I19

**SECTION I** : The first moving average of lift cycles per hour TI S The first moving average calculation is performed on the MRS assembly when the external lift component history card record reflects that the MRS assembly has reached its first 250 hours TI S. To perform the calculation, divide the total number of lift cycles performed during the first 250 hours TI S by 250. The result will be the first moving average calculat ion of lift cycles per hour TIS. **SECTION II** : Subsequent moving average of lift cycles per hour TIS Subsequent moving average calculations are performed on the MRS assembly at intervals of 50 hour TIS after the first moving average calculation. Subtract the total number of lift cycles performed during the first 50 - hour TIS interval used in the previous moving average calculation from the total number of lift cycles performed on the MRS assembly during the previous 300 hours TI S. Divide this result by 250. The result will be the next or subsequent moving average calculation of lift cycles per hour TIS. **SECTION III** : Sample calculation for subsequent 50 hour TI S intervals Assume the total number of lift cycles for the first 50 hour TI S interval used in the p revious moving average calculation = 450 lift cycles and the total number of lift cycles for the previous 300 hours TI S = 2700 lift cycles. The subsequent moving average of lift cycles per hour TIS = (2700 - 450) divided b y 250 = 9 lift cycles per hour TIS.20

**( i**  **) Subject**  . Joint Aircraft Service Component (JASC) Code: 6320, Main Rotor Gearbox. Issued in Fort Worth, Texas, on April 16, 2013. Lance T. Gant, Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.